With the extended bandwidth and increased operating speed of a mobile communication network, services or distribution using packet communication may be expected to be increasing. Under these situations, a service in which, when two or more (for example, an N-number of) terminals take part together to form a group of terminals, packet data sent from a first terminal is received and copied and the so copied data are sent to (N−1) terminals other than the first terminal, have already been commenced under the name of PoC (Push to talk over Cellular) insofar as speech is concerned.
In time to come, similar services targeted for a video signal (video PoC or video sharing) are expected to be commenced with the progress of IMS (IP Multimedia Subsystem).
In this case, a video signal is compression-encoded on a terminal side in order to transmit a signal with high efficiency at a low bit rate. Examples of known schemes include ITU-T (International Telecommunication Union Telecommunication Standardization Section) Recommendations H.263 and MPEG-4 (Moving Picture Experts Group phase 4) internationally standardized by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission).
With the H.264/MPEG-4 AVC (Advanced Video Coding), internationally standardized by ITU-T and ISO/IEC, a moving picture signal may be transmitted more efficiently than is possible with the aforementioned moving picture compression encoding scheme.
As a system for media distribution, there is disclosed in Patent Document 1, a configuration in which a server, relaying multimedia communication data, converts multimedia communication data into an output video information, matched to the media reproduction capability of a receiving terminal, before transmitting the information to the receiving terminal. There is also disclosed in Patent Document 2 a configuration in which the encoded information in need of a larger display capability is converted into the encoded information capable of being displayed with a preset display capability, and both the original encoded information and the converted encoded information are provided by a data server apparatus on a local area network. A contents information reproduction terminal acquires the encoded information (multimedia data) matched to its own display level along with a decoding program for reproduction. There is disclosed in Patent Document 3 a configuration of a multi-cast network in which, on detection of change of a channel request that specifies a requested channel corresponding to a multi-cast group, a retained intra-frame of the requested channel is transmitted by way of uni-cast communication. Patent Document 4 discloses a configuration in which, if a content requested is issued by a client, a server apparatus converts the format, by its self, responsive to the contents. If the server apparatus is unable to convert the format, but there is another server apparatus which is able to do so, the server apparatus may request another server apparatus to convert the format, and to transmit the converted format to the client.
As a system for posting an advertisement, there is disclosed in Patent Document 5, a configuration in which an advertisement in a broadcast data stream is identified, and in which an advertisement in a broadcast program in a broadcast data stream, and an advertisement schedule, inclusive of the information for identifying the location of advertisement, are updated. In reproduction, an advertisement or an alternative advertisement is posted in the above location or in a further location in the program. In the Patent Documents 1 to 5, there are disclosed configurations completely different from the configuration of a server apparatus in which at least two terminals take part to form a group of terminals, a stream or a packet, containing a video signal, is received from a first one of the terminals and copied, and in which the stream or packet, thus copied, is transmitted to those terminals that are different from the first terminal.    [Patent Document 1] JP Patent Kokai Publication No. JP-P2002-297496A    [Patent Document 2] JP Patent Kokai Publication No JP-P2004-272631A    [Patent Document 3] JP Patent Kokai Publication No. JP-P2005-124193A    [Patent Document 4] JP Patent Kokai Publication No. JP-P2008-5254A    [Patent Document 5] JP-Patent Kohyo Publication. No. JP-P2006-519525A